/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { Headers } from '../Headers'
import { BufferedSource } from '../okio/BufferedSource'

/**
 * Parse all headers delimited by "\r\n" until an empty line. This throws if headers exceed 256 KiB.
 */
export class HeadersReader{
  source: BufferedSource
  private static HEADER_LIMIT = 256 * 1024
  constructor(source: BufferedSource) {
    this.source = source
  }

  private headerLimit = HeadersReader.HEADER_LIMIT

  /** Read a single line counted against the header size limit. */
  async readLine(): Promise<string> {
    let line: string = await this.source.readUtf8LineStrict(this.headerLimit)
    this.headerLimit -= line.length
    return line
  }

  /** Reads headers or trailers. */
  async readHeaders(): Promise<Headers> {
    let result = new Headers.Builder()
    while (true) {
      let line = await this.readLine()
      if (line === '') break
      result.addLenientWithLine(line)
    }
    return result.build()
  }

}
